Single or collection resources

[Doug Tody]

Hi Markus -

Any of these approaches would work.  In general the same data can
be available from multiple services (e.g. due to replication of a
popular collection) hence this situation cannot really be avoided.

Re option #2, while the RMI cannot fully describe the data in this case
since there are multiple individual collections, the SIA query response
can, since each image is separately described.  Hence something
like CREATOR (DataID.Creator), COLLECTION, PublisherDID, etc. can
be specified separately for each image.  This metadata is included
directly in the query response, although COLLECTION could be used
to obtain additional information about a data collection from the
registry entry for the collection.

This would be true for either SIAV1 or V2, however only V2 will have
this richer metadata.

 	- Doug


On Tue, 4 Aug 2009, Markus Demleitner wrote:

> Dear DAL folks,
>
> here is a somewhat "soft" question for a change:
>
> I have various image sets, all of them small-ish or medium sized
> (i.e., several 100 to a few 10000s of images); some of them can be
> grouped "thematically", e.g.,
>
> * Ancient plate scans from various observatories
> * Images of gravitational lenses from various observatories
>
> I can see three strategies to publish them via SIAv1 (disclaimer: I'm
> not really up to date on SIAv2 discussions; but then I'd like to have
> a short-term, SIAv1-based solution anyway):
>
> (1) provide a SIA service for each data set individually
> (2) provide SIA service for each "topic"
> (3) do both.
>
> Now, (1) is nice because it lets me specify meaningful RMI-style
> metadata (creator, source, etc), so things will look nice in the
> registry and users have a fair chance to read up on where the data
> actually came from.  Downsides of this include that I'll clutter up
> result displays in VO-wide Astroscopes  and similar applications, and
> clients will have to issue potentially quite a number of queries to
> my server with all the incurred overhead.
>
> (2) is attractive because people interested in, say, gravitational
> lenses would have to query just one service on my server and get
> everything I have.  But the metadata will be extremely ugly ("creator:
> various"), and as far as I can see, SIAv1 does not provide a standard
> mechanism to say something like "RMI metadata for this row can be
> obtained here".
>
> (3) could be a solution, giving rich metadata on the services but
> still providing a service giving people all pertinent information in
> one go.  But of course I'll still clutter up Astroscope and friends,
> and even worse, each result will show up twice, once in the
> collection service, and once in the individual services.
>
> So, I think there's no ideal solution -- but maybe others have
> better ideas or at least opinions on what a good VO citizen should
> do?
>
> Cheers,
>
>        Markus
>